Washing machines have mainly employed induction motors (e.g. refer to Patent Documents 1 and 2); however, in recent years, brushless motors have been increasingly used in washing machines in order to obtain higher efficiency for an energy saving purpose. When the brushless motor is mounted in washing machines, it is critical for the motor to take measures against moisture, because its drive circuit must be protected from dew formation and moisture.
Drip-proof and moisture-proof structures of the drive circuit can be achieved by molding a motor stator and the drive circuit into one unit with resin (e.g. refer to Patent Document 3). However, if there is a component or a soldered section vulnerable to the molding resin injected at a high temperature and a high pressure, the component or the soldered section must be sealed with resin that is hardened at a low temperature and a low pressure (e.g. refer to Patent Document 4). In this case, it is sometimes needed to ease the stress produced during the hardening of the sealing resin.
Patent Document 1: Unexamined Japanese Patent Application Publication No. 2004-112866
Patent Document 2: Unexamined Japanese Patent Application Publication No. H04-256791
Patent Document 3: Unexamined Japanese Patent Application Publication No. H11-155249
Patent Document 4: Unexamined Japanese Patent Application Publication No. 2001-61258